Adult sryllian flies are harmless and only eat nectar on the rare occasions when they need to feed. They hatch from the water with tough, shimmering exoskeletons and discard their casings, which local mountain farmers will often collect to sell to traders in Synara. Adult flies usually mate shortly after they metamorphose, and may return annually to the stream where they hatched in order to reproduce. The flies have a wingspan of about four inches when fully grown, large enough to carry small items like gold flakes and single gemstones. The flies are quite sharp companions for insects, and can be trained to recognize and locate certain metals or gems. Large flies may even retrieve small samples and bring them to their caretakers, making them especially valuable for people seeking such valuables. Magi will occasionally use them to locate special ingredients for spells or charms, though the relatively short lifespan of the insects compared to other companions and the time it takes to effectively train them limits their popularity primarily to Keep entomologists.

About a month into spring, when the weather in the foothills of the Alasres becomes warm enough to melt the snow for a few days, sryllian flies emerge in colorful blue-and-gold swarms and leave behind the casings that protected them as larvae. Unlike the other flies in the mountains, sryllian flies can live for several years as adults and are often adopted by insect enthusiasts for their beautiful appearance and aptitude for treasure-hunting. While adult sryllian flies are attracted to any reflective surface and can be trained to find certain rare substances, hatchlings go a step further and instinctually gather flakes of shiny metals and gems to create elaborate casings that are not only beautiful to look at, but also have protective capabilities. Suited to guard the hatchlings' delicate bodies from harm, these casings retain their magical properties after the flies discard them. Jewelry made from sryllian fly casings is valuable, as enough of them will protect a wearer from certain physical injuries. However, buyers looking to make armor from the casings should be cautious, as the protection they provide is more limited than it seems; plenty of foolish warriors have died thinking themselves invincible if wearing a sryllian fly ornament.